Looking for something different in the aquarium hobby? Then a brackish water aquarium may be just the endeavor for you! They are easy to maintain since the fish from brackish waters are designed to withstand frequent salinity and water changes, unlike both fresh and saltwater fish. The following is a basic overview of how to set up and maintain a tropical brackish aquarium. Brackish is a mixture of fresh and salt water. In the wild, it is found naturally occurring in estuaries, while as a hobby it can be obtained by mixing light amounts of marine or reef salt with RO water. Because a lower amount of salt is needed, the salinity can range between 1.005-1.012.

Research

The first step before any well-planned aquarium is research. Take the time to think about what kinds of fish you would like to keep. By pre-planning you are better assured that the fish you choose will be appropriate tank mates. Keep in mind when planning your tank that many brackish species need a higher salinity as they mature. Be sure the fish you choose have similar salinity requirements to each other for their entire lives.

Aquarium Size

Almost any size aquarium is suitable for brackish fish. However, the smaller the aquarium, the smaller and fewer fish you can put in it. Due to the adult size of many brackish fish, bigger is better. A larger ecosystem can better handle the daily fluctuations in water quality and salinity than a smaller ecosystem, absorbing more toxins and reducing stress to the fish. Before buying your aquarium, take into account the adult size of the fish you are going to purchase and the general rule: one inch of the fish body (not including fins) per two gallons of water in the brackish aquarium.

Setting Up Your Aquarium

You will need good filtration, either a hang-on power filter, a canister filter, or a wet-dry system (for larger or heavily stocked tanks). Check with one of our staff members, as these types vary with the size of the aquarium, and the fish desired.

The substrate or gravel for the brackish aquarium should be crushed coral or sand. This can be any saltwater aragonite.

A heater is required for brackish set-ups; set your temperature between 76 and 80 degrees.

Lighting is another consideration, but how much you will need varies. If you are only keeping fish (no live plants) a simple fluorescent bulb fixture will suffice. If you find you have an algae problem, reduce the hours the light is on.

Be sure to have test kits on hand to monitor your water chemistry. Test the water in your new aquarium at least twice a week for pH, ammonia, nitrite, and nitrate. Carbonate hardness are also good tests to have available. The pH levels in brackish aquariums vary depending on the type of habitat, falling between 7.5 and 8.5.

Brackish aquariums require marine salt mixes and not freshwater salt. Mix your salt directly in the aquarium when first setting up. After the tank is established, mix any salt in a separate bucket before adding it to the tank. Check the salinity with a hydrometer or refractometer. Salinity (or specific gravity) requirements vary with the fish you choose. Many brackish estuary fish will require slow increases in salinity as they grow to adults, eventually reaching full marine salinity.

Recommended Fish and Plants to Add

There are more fish than one would think for brackish systems. Some are more commonly found in freshwater aquariums and can handle lower levels with no adjustments or increases over time. While others are found in marine aquariums and will need the salinity to rise to a marine level, around 1.022, as they mature. Because most plants won’t tolerate salt, they can be tricky to add, there are some plants that might be a little more tolerable but be prepared for losses. If you plan on adding plants, lower salinity would be best. Some macroalgae would be more suitable for any range of salinity. The most important thing to remember is that most fish will come either fully fresh or saltwater. So, any acclimation must be done carefully and slowly for a few hours with an air stone to allow for more oxygen.

Lower Salinity Fish

• Guppies
• Mollies
• American Flagfish
• Figure 8 Puffer
• Bumblebee Goby
• Brackish Moray Eel
• Zebra Blenny

Higher Salinity Fish (When Mature)

• Green Spotted Puffer
• Mono Argenteus
• Scats
• Mollies

Brackish Invertebrates

• Amano Shrimp
• Nerite Snails
• Red Claw Crab / Fiddler
• Hermit Crab
• Dove Snail
  

Lower Salinity Plants

• Mangrove
• Anubias
• Java Fern
• Java Moss
• Anachris

Higher Salinity Plants & Macroalgae

• Mangrove
• Chaeto
• Cavlera Prolifera
• Ulva
• Ogo
• Turtle Grass